The Basilica of San Celso is a Romanesque-style religious building located in Milan. Built to preserve the relics of San Celso, the saint linked to San Nazario, the building was erected in the 4th century but rebuilt in the 11th. In the late 18th century, the front of the church was demolished, making it more backward today than the façade of the nearby Sanctuary.

The brick facade was rebuilt in the neo-Romanesque style in the 19th century; decorated with a rose window and a Romanesque portal with zoomorphic representations. The bell tower dates back to the 11th century. Inside, the Basilica consists of three short aisles of two spans each, with a cross roof.